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Biomedical subjects

R Norton

Publications and source records attributed to R Norton.

At least 37 records · Page 2Linked to original sources
PubMed2002

Pseudomonas fluorescens pseudobacteraemia: a cautionary lesson.

OBJECTIVES: To describe an outbreak of pseudobacteraemia caused by Pseudomonas fluorescens in a paediatric population. To document and highlight the effect this outbreak had on clinical management and the steps taken to determine the source. METHODS: A clinical and microbiological investigation was carried out into a cluster of 38 pseudobacteraemias caused by Pseudomonas fluorescens in paediatric patients over a 10 month period. RESULTS: The source of the outbreak of pseudobacteraemia was found to be contaminated lithium heparin tubes, which were being filled prior to the filling of the blood culture bottle. Cultures of the same tubes yielded Pseudomonas fluorescens. As a result of the initial positive blood cultures, clinical management was altered in 18 cases. A staff education programme was instituted and eventually resulted in a cessation of the pseudobacteraemia. CONCLUSIONS: Pseudobacteraemias are a major cause of potentially inappropriate therapy in febrile children. Attention to detail in the collection of blood cultures can help reduce this outcome. Staff involved in the collection of blood cultures need to be aware of this potential source of contamination.

Adolescent↗
PubMed2001

Prevalence of driver sleepiness in a random population-based sample of car driving.

STUDY OBJECTIVES: To obtain reliable estimates of the prevalence of driver sleepiness. DESIGN: A two-stage cluster sampling technique was employed to obtain a sample of car drivers representative of time spent driving on public roads in a geographically defined region. Data were collected by interviewer-administered questionnaire, and analysed in accordance with the sampling design. SETTING: The Auckland region of New Zealand, between April 1998 and July 1999. PARTICIPANTS: 588 drivers of cars and other light vehicles recruited at 69 roadside survey sites. MEASUREMENTS AND RESULTS: Of 746 eligible participants, 79% were interviewed, 12% refused, 8% were untraceable, and 1% were unable to give informed consent. From this sample we estimated that 58.7% of driving was undertaken by men. The vast majority of driving (90.8%) was undertaken by drivers with Epworth Sleepiness scores in the normal range (<10), but a significant minority was undertaken by drivers with one or more characteristics likely to impair alertness. 3.1% had < or = 5 hours sleep in the previous 24 hours, and 21.9% had < or = 4 full nights sleep in the previous week. The triad of symptoms associated with sleep apnea (snoring, choking, and breathing pauses while sleeping) was present in 1.6%; and 8.1% worked a pattern of shifts likely to interfere with normal sleep. CONCLUSION: The prevalence of sleepiness amongst a random sample of New Zealand car driving was low, and less than suggested by previous studies.

Adolescent↗
PubMed2001

The role of driver sleepiness in car crashes: a systematic review of epidemiological studies.

To assess the available evidence for a causal role of driver sleepiness in car crashes or car crash injury, and to quantify the effect, a systematic review of the international literature was conducted. The review included all studies with a fatigue-related exposure measure, a crash or crash injury outcome measure and a comparison group, regardless of publication status, language or date of the study. Eighteen cross-sectional studies and one case-control study fulfilled the inclusion criteria. The fatigue-related exposures investigated in these studies were sleep disorders (n = 14), shift work (n = 2), sleep deprivation/fragmentation (n = 1), and excessive daytime sleepiness (n = 2). Only one study used an injury outcome measure. Studies were limited in their ability to establish a causal relationship by their design, by biases, and in many cases, by small sample sizes. The better quality cross-sectional studies were suggestive of a positive relationship between fatigue and crash risk, but could not provide reliable estimates of the strength of the association. The case-control study provided moderately strong evidence for an association between sleep apnoea and risk of driver injury, with an adjusted odds ratio of 7.2 (95% confidence interval 2.4-21.8). We conclude that the direct epidemiological evidence for a causal role of fatigue in car crashes is weak, but suggestive of an effect. To estimate the burden of injury due to fatigue-related crashes in the population, information is required from well-designed observational epidemiological studies about the prevalence of fatigue in the car driving population and the size of the risk this confers.

Accidents, Traffic↗
PubMed2001

Fifteen-year experience with the mitral Carpentier-Edwards PERIMOUNT pericardial bioprosthesis.

BACKGROUND: This multicenter study concerning the mitral PERIMOUNT valve previously reported clinical results at 12 years; this report updates the performance to 15 years postoperatively. METHODS: The 435 patients (mean age 60.7+/-11.6 years; 41.1% male) underwent implantation with the PERIMOUNT valve between 1984 and 1989 at seven institutions. Follow-up was complete for 96.1% of the cohort. The mean follow-up was 8.1+/-4.4 years (range 0 to 15.4 years) for a total of 3492 patient-years. RESULTS: There were 34 (7.8%) operative deaths, one (0.2%) valve related. The late mortality rate was 5.3%/patient-year (2.2%/patient-year valve related). At 14 years, the overall actuarial survival rate was 37.1%+/-3.3% (63.1%+/-4.4% valve related). Actuarial freedom from complications at 14 years was as follows: thromboembolism, 83.8%+/-3.2% (1.1%/patient-year); hemorrhage, 86.6%+/-3.2% (1.1%/patient-year); and explant due to structural valve deterioration (SVD), 68.8%+/-4.7%. Actual freedom from explant due to SVD was 83.4%+/-2.3%. Rates of structural failure decreased with increasing age at implant. CONCLUSIONS: The Carpentier-Edwards PERIMOUNT Pericardial Bioprosthesis is a reliable choice for a tissue valve in the mitral position, especially in patients more than 60 years of age.

Actuarial Analysis↗
PubMed2001

Burkholderia pseudomallei virulence: definition, stability and association with clonality.

Clinical presentations of melioidosis, caused by Burkholderia pseudomallei are protean, but the mechanisms underlying development of the different forms of disease remain poorly understood. In murine melioidosis, the level of virulence of B. pseudomallei is important in disease pathogenesis and progression. In this study, we used B. pseudomallei-susceptible BALB/c mice to determine the virulence of a library of clinical and environmental B. pseudomallei isolates from Australia and Papua New Guinea. Among 42 non-arabinose-assimilating (ara(-)) isolates, LD(50) ranged from 10 to > 10(6) CFU. There were numerous correlations between virulence and disease presentation in patients; however, this was not a consistent observation. Virulence did not correlate with isolate origin (i.e. clinical vs environmental), since numerous ara(-) environmental isolates were highly virulent. The least virulent isolate was a soil isolate from Papua New Guinea, which was arabinose assimilating (ara(+)). Stability of B. pseudomallei virulence was investigated by in vivo passage of isolates through mice and repetitive in vitro subculture. Virulence increased following in vivo exposure in only one of eight isolates tested. In vitro subculture on ferric citrate-containing medium caused attenuation of virulence, and this correlated with changes in colony morphology. Pulsed-field gel electrophoresis and randomly amplified polymorphic DNA typing demonstrated that selected epidemiologically related isolates that had variable clinical outcomes and different in vivo virulence were clonal strains. No molecular changes were observed in isolates after in vivo or in vitro exposure despite changes in virulence. These results indicate that virulence of selected B. pseudomallei isolates is variable, being dependent on factors such as iron bioavailability. They also support the importance of other variables such as inoculum size and host risk factors in determining the clinical severity of melioidosis.

Animals↗
PubMed2001

Random errors in the measurement of 10 cardiovascular risk factors.

Random errors in the measurement of 10 commonly investigated cardiovascular risk factors (systolic and diastolic blood pressure, blood cholesterol, blood glucose, pulse rate, body mass index (BMI), cigarette consumption, passive smoking, alcohol intake and physical exercise) were assessed in a general population cohort (n = 2517) and a workforce cohort (n = 8008). Random errors were estimated from regression dilution ratios (lower ratios imply greater random error, and a ratio of one implies no random error). All of the risk factors, except for BMI (which had regression dilution ratios of 0.93 and 0.98 in the two cohorts), were measured with substantial levels of random error. Particularly low regression dilution ratios were observed for physical exercise (0.28 and 0.39) and pulse rate (0.47 and 0.56). For each of these risk factors, with the possible exception of BMI, associations with long-term average values could be importantly biased toward the null unless appropriate corrections are made.

Bias↗
PubMed2001

Recurrent Methylobacterium mesophilicum sepsis associated with haemodialysis.

Methylobacterium mesophilicum is an environmental organism that has infrequently been implicated as a human pathogen. Most reported cases are in immunocompromised hosts. The natural ecology of this organism is related to vegetation or soil. We report the case of a 51-year-old man who developed a recurrent bacteraemia with this organism while receiving haemodialysis through an indwelling intravascular catheter. The literature on the clinical significance of this organism is reviewed together with specific microbiological identifying features which could be of use in the routine diagnostic laboratory.

Catheterization, Central Venous↗
PubMed2001

Is physical activity protective against hip fracture in frail older people?

BACKGROUND: there is limited evidence of a protective effect of physical activity in preventing hip fractures among older people living in institutions and in those aged 80 or over. OBJECTIVE: to examine the relationship between physical activity and risk of hip fracture in frail older people. DESIGN: a case-control study. SETTING: Auckland, New Zealand. SUBJECTS: a random sample of individuals hospitalized with a fracture of the femoral neck (n=911) and 910 randomly selected age- and sex-matched individuals from the lists of a random sample of general practitioners. METHODS: we sought information on physical activity and other potential risk factors for hip fracture from cases and controls, using a standardized interviewer-administered questionnaire. We conducted multivariate analyses, separately for those living in private homes and residential institutions. RESULTS: increasing hours of physical activity per week protected against the risk of hip fracture among individuals living in private homes, including those who are over 80. However, among individuals living in institutions, physical activity levels were extremely low (<15% participated in >/=2 h per week) and there was limited evidence of a protective effect. CONCLUSIONS: efforts to prevent hip fractures in individuals living in care homes and institutions should focus on passive interventions which are known to be effective.

Activities of Daily Living↗
PubMed2001

Outcomes of patients using a tiered trauma response protocol.

OBJECTIVES: This study evaluated processes of care and outcome for injured patients at a Level I trauma center who had been either treated as a full trauma team activation (FULL) or managed with a modified trauma team activation (MOD). METHODS: A retrospective methodology was used to evaluate all patients entered into the regional trauma system and transported from the scene to a Level I trauma center. Patients treated during a 2-year period of exclusively FULL trauma team protocols were compared with patients managed during a subsequent 2-year period after implementation of a two-tiered response. In the later era, trauma system patients were designated before hospital arrival as either FULL or MOD trauma team responses. An additional case-control analysis was conducted on a subset of MOD trauma team response patients who were undertriaged; that is, in retrospect, they met criteria for a FULL response. The outcomes in the case-control group were compared by chi2 tests and Mann-Whitney U tests. Statistical significance was assumed for p < 0.05. RESULTS: During the presystem period, 1,740 patients were transported as trauma system entries to Oregon Health Sciences University. During the postsystem period, 2,333 patients were transported to Oregon Health Sciences University as either MOD trauma system entries (1,272 [55%]) or as FULL trauma system entries (1,061 [45%]). Postsystem patients had longer time intervals in the emergency department compared with presystem patients. Death rates for patients who died in the emergency department or before hospital discharge were similar. Among patients who were designated as MOD trauma system entries and were subsequently categorized as meeting FULL trauma team criteria, mortality rate was low. CONCLUSION: Implementation of the tiered response protocol led to a substantial change in the operational response in the emergency department. Although processes of care were nominally prolonged, adverse consequences were not identified. We concluded from this quality improvement review that implementation of a tiered response protocol was satisfactory and improved efficiency. Further work is required to improve accuracy of the categorization of trauma system patients as either MOD or FULL trauma codes.

Adult↗
PubMed2001

Demonstration of different patterns of musculoskeletal, soft tissue and visceral involvement in melioidosis using 99m Tc stannous colloid white cell scanning.

Melioidosis is an infectious disease that can present with multiple foci of disease involvement. Assessment of disease extent can be difficult, especially in musculoskeletal, visceral and soft tissue infection. This study examined the usefulness of white cell scans in this condition. 99mTc stannous colloid white cell scanning was performed in 21 patients with culture-proven melioidosis. Scan results were compared with clinical assessment and correlated with other forms of imaging. White cell scans demonstrated all but one of the clinically apparent sites of musculoskeletal, visceral and other soft tissue infection. Unsuspected disseminated soft tissue lesions were seen in two patients, including femoral node uptake in both, and these patients subsequently presented with relapsing musculoskeletal disease. Unsuspected musculoskeletal disease was found in one patient. Clinically suspected musculoskeletal disease was accurately excluded by white cell scan in another patient. The results of white cell scanning were also examined in disease of other viscera. Renal and prostatic disease were visualized. Unsuspected parotid involvement was found in two patients. Only one of two spinal lesions was visualized. Pulmonary disease was not necessarily associated with abnormal uptake. White cell scanning is a quick and effective way of assessing the extent of musculoskeletal, visceral and soft tissue disease in melioidosis.

Adult↗
PubMed2001

Vibrio cholerae non-O1 facial cellulitis in a North Queensland, Australian child.

Vibrio cholerae is an uncommon cause of cellulitis in Australia. Most reported cases worldwide have involved marine or brackish water contact. A recognized risk factor for acquiring this infection is chronic liver disease secondary to hepatitis B. We describe a case of extensive facial cellulitis caused by Vibrio cholerae non-O1, non-0139, in an 11-year-old indigenous girl from North Queensland, Australia, who was hepatitis B surface antigen-negative. Treatment consisted of extensive debridement, antibiotics, hyperbaric oxygen and facial reconstructive surgery. Early microbiologic diagnosis and a combined therapeutic approach are important in the management of this condition.

Australia↗
PubMed2001

Effects of folate supplementation on two provisional molecular markers of colon cancer: a prospective, randomized trial.

OBJECTIVES: Dietary folate intake is inversely associated with the risk of colorectal cancer. This study investigated the effect of folate supplementation on genomic DNA methylation and DNA strand breaks in exons 5-8 of the p53 gene of the colonic mucosa, two provisional biomarkers of colon cancer. METHODS: Twenty subjects with adenomas were randomized to receive either folate (5 mg/day) or placebo for 1 yr after polypectomy. At baseline, 6 months and 1 yr, systemic and colonic measures of folate status were determined, as were the biomarkers mentioned earlier. RESULTS: Folate supplementation increased serum, red blood cell and colonic mucosal folate concentrations (p < 0.02). Folate supplementation also increased the extent of genomic DNA methylation at 6 months and 1 yr (p = 0.001), whereas placebo administration was associated with an increase in the extent of genomic DNA methylation only at 1 yr. Similarly, folate supplementation decreased the extent of p53 strand breaks in exons 5-8 at 6 months and 1 yr (p < 0.02), whereas placebo administration was associated with a decrease in the extent of p53 strand breaks only at 1 yr. CONCLUSIONS: Both of these provisional biomarkers of colon cancer underwent accelerated improvement at 6 months with folate supplementation. However, these markers also improved with placebo at 1 yr. Therefore, potential confounding factors that seem to modulate these biomarkers need to be identified and corrected in order for these markers to serve as suitable surrogate endpoints in folate chemoprevention trials.

Adenoma↗
PubMed2001

Use of nucleotides in weanling rats with diarrhea induced by a lactose overload: effect on the evolution of diarrhea and weight and on the histopathology of intestine, liver and spleen.

Until recently, dietary sources of nucleotides were thought not to be essential for good nutrition. Certain states with higher metabolic demands may require larger amounts that cannot be provided by endogenous production. The objective of the present study was to determine the action of nucleotides on the recovery from lactose-induced diarrhea in weaned rats. Thirty-six weanling Fisher rats were divided into two groups. Group 1 received a standard diet and group 2 received a diet containing lactose in place of starch. On the 10th day, six animals per group were sacrificed for histopathological evaluation. The remaining animals were divided into two other subgroups, each with 6 animals, receiving a control diet, a control diet with nucleotides (0.05% adenosine monophosphate, 0.05% guanosine monophosphate, 0.05% cytidine monophosphate, 0.05% uridine monophosphate and 0.05% inosine monophosphate), a diet with lactose, and a diet with lactose and nucleotides. On the 32nd day of the experiment all animals were sacrificed. Animals with diarrhea weighed less than animals without diarrhea. The introduction of nucleotides did not lead to weight gain. Mean diet consumption was lower in the group that continued to ingest lactose, with the group receiving lactose plus nucleotides showing a lower mean consumption. Animals receiving lactose had inflammatory reaction and deposits of periodic acid-Schiff-positive material in intestinal, hepatic and splenic tissues. The introduction of nucleotides led to an improvement of the intestinal inflammatory reaction. In lactose-induced diarrhea, when the stimulus is maintained--lactose overload--the nucleotides have a limited action on the weight gain and on recovery of intestinal morphology, although they have a protective effect on hepatic injury and improve the inflammatory response.

Analysis of Variance↗
PubMed2001

Colonic mucosal concentrations of folate are accurately predicted by blood measurements of folate status among individuals ingesting physiologic quantities of folate.

Folate status is inversely related to the risk of colorectal cancer. Whether conventional blood measurements of folate status accurately reflect folate concentrations in the colorectal mucosa has been a controversial topic. This is an important issue because accurate measures of folate status in the colorectal mucosa are important for ascertaining the risk of colorectal cancer in epidemiological studies and for determining the effects of folate supplementation in clinical trials. We examined whether conventional blood measurements of folate and a more sensitive, inverse indicator of systemic folate status, serum homocysteine, accurately reflect folate concentrations in human colonic mucosa obtained by endoscopic biopsy. Study subjects (n = 20) were participants in a randomized trial that investigated the effect of folate supplementation (5 mg daily for 1 year) on provisional molecular markers of colon cancer. Blood samples and biopsies of normal rectosigmoid mucosa were obtained at baseline, at 6 months, and at 1 year. Serum, RBC, and colonic mucosal folate and serum homocysteine concentrations were determined. Colonic mucosal folate concentrations correlated directly with serum folate concentrators at each time point (r = 0.572-0.845; P < 0.015) and with RBC folate concentrations at 6 months and 1 year (r = 0.747-0.771; P < 0.001). Colonic mucosal folate concentrations correlated inversely with serum homocysteine concentrations at each time point (r = -0.622-0.666; P < 0.008). Systemic measures of folate status did not correlate with colonic mucosal folate concentrations among individuals receiving supplemental folate. Our observations indicate that colonic mucosal concentrations of folate may be predicted accurately by blood measurements of folate status only among individuals not ingesting supraphysiological quantities of folate.

Adenoma↗
PubMed2001

Pacifichem 2000: biomolecular structure and NMR.

Nuclear magnetic resonance (NMR) spectroscopy continues to expand its applications in the areas of pharmaceutical discovery and development and biotechnology. These and other applications were reviewed in a symposium that ran over 3 days of the Pacifichem 2000 congress. This summary focuses on development in NMR relevant to the pharmaceutical and biotechnology industries, as well as some specific applications that illustrate future directions.

Journal Article↗
PubMed2000

Visual impairment and risk of hip fracture.

As part of a case-control study, the Auckland Hip Fracture Study (1991-1994), the authors examined associations between impaired vision and risk of hip fracture. Subjects (911 cases and 910 controls aged 60 years or older) completed a questionnaire and had vision measurements taken, including measurements of visual acuity and stereopsis (depth perception). Binocular visual acuity worse than 20/60 was statistically significantly associated with increased risk of hip fracture after adjustment for age, sex, proxy response, hours of activity per week, and height (odds ratio (OR) = 1.5; 95% confidence interval (CI): 1.1, 2.0), as was having poor vision (less than 20/100) in both eyes (OR = 2.4; 95% CI: 1.0, 6.1). Having no depth perception was associated with increased risk (OR = 6.0 95% CI: 3.2, 11.1), as were categories of decreasing stereopsis (trend p = 0.0001), self-reported poor vision (OR = 1.4; 95% CI: 1.0, 1.9), not wearing glasses at the time of the fall (OR = 1.2; 95% CI: 1.0, 1.6), and increasing time since the last eye examination (trend p = 0.03). The population attributable risk of hip fracture due to poor visual acuity or stereopsis was 40%. Visual factors are important fall-related factors which influence risk of hip fracture. Risk of hip fracture may be decreased by correcting refractive error, improving stereopsis, and administering regular eye examinations.

Accidental Falls↗